In prior art there are speech coders specifically designed to code speech signals by basing the coding upon a source model of the signal, i.e. the human vocal system. These coders cannot handle arbitrary audio signals, such as music, or any other non-speech signal. Additionally, there are in prior art music-coders, commonly referred to as audio coders that base their coding on assumptions on the human auditory system, and not on the source model of the signal. These coders can handle arbitrary signals very well, albeit at low bit rates for speech signals, the dedicated speech coder gives a superior audio quality. Hence, no general coding structure exists so far for coding of arbitrary audio signals that performs as well as a speech coder for speech and as well as a music coder for music, when operated at low bit rates.
Thus, there is a need for an enhanced audio encoder and decoder with improved audio quality and/or reduced bit rates.